A number of disk drives using a range of recording-disk types including optical disks, magneto-optical disks, and flexible magnetic-recording disks are available. These disk drives also include HDDs which are widely employed in computers as data-storage devices, and which are indispensable in existing computer systems. Furthermore, because of the superior characteristics of HDDs, the use of a HDD is not limited to computer systems, and the use of HDDs has been expanded to include video image recording and reproduction apparatuses, and car navigation systems.
A HDD includes a magnetic-recording disk for storing data, a head-slider for reading form, and/or writing data to, the magnetic-recording disk, and an actuator for moving the head-slider to a designated position on the magnetic-recording disk. The actuator is driven by a voice-coil motor (VCM), and oscillates about a pivot shaft. As a result, the actuator causes the head-slider to move over the rotating magnetic-recording disk in substantially the radial direction of the magnetic-recording disk.
The head-slider is able to be moved to a designated track on the magnetic-recording disk, and data processing is able to be performed by reading data from, or writing data to, this track. The head-slider includes a magnetic-recording head for performing data processing by reading data from, or writing data to, the track. The actuator includes an elastic suspension, and the head-slider is fastened to the suspension.
The head-slider is able to fly over the magnetic-recording disk at a predetermined fly height between the head-slider and the magnetic-recording disk due to the balance that exists between the pressure generated by the viscosity of the air between the rotating magnetic-recording disk and the air-bearing surface (ABS) of the slider opposing the magnetic-recording disk, and a load that is applied by the suspension towards the surface of the magnetic-recording disk. The suspension is fabricated to allow the slider to track across the surface of the magnetic-recording disk in such a way that the slider is able to be tilted in a predetermined direction in order to compensate for magnetic-recording disk runout and other factors.
The actuator typically includes a carriage, which is also known as an E-core or comb, which includes a VCM coil and one arm, or a plurality of arms, a head-gimbal assembly (HGA) affixed to the distal end of the arm, or arms, and a pivot-bearing assembly affixed within a hole disposed in the center of the carriage. The HGA includes the suspension and the head-slider. The actuator oscillates about the pivot-bearing assembly as a result of a driving force applied by the VCM coil.
Increased HDD recording density has been accompanied by increased track density and further increased positioning precision. Increasing the track density, which may be obtained by narrowing the track interval, has lead to widening the head positioning control bandwidth. To do this, the head-slider is supported, and the bandwidth of the actuator for moving the head-slider is widened. To widen the bandwidth of the actuator, reducing actuator vibration characteristics is useful for increasing HDD performance.